vid wrote:

edfed: do you actually USE fasmd in pure dos, or do you just want it?

I DO USE it in DOS

You will want to use the r6 test release if you plan to use more than
500MB.

Also it reportedly doesn't work on Cyrix

I also did play with DOS interface a bit, I fixed some bugs and also managed to free some space under the 64k code limit, so that I still don't have to get rid of the unREAL mode from the DOS interface.

@echo off
:: Using GNU/DJGPP sed 4.1.5 to shave a few bytes from FASM 1.67.26   

:: 1). show only these lines before and after
:: sed -n "/add[ \t][ \t]*\(e\?[a-z][a-z]\)[ \t]*,[ \t]*2$/{p;s//rept 2 { inc \1 }/p}" .../*.*
:: 2). show affected line numbers only
:: sed -n "/add[ \t][ \t]*\(e\?[a-z][a-z]\)[ \t]*,[ \t]*2$/=" .../*.*
:: 3). count total affected lines
:: sed -n "/add[ \t][ \t]*\(e\?[a-z][a-z]\)[ \t]*,[ \t]*2$/=" .../*.* | sed -n $=
:: 4). edit "in place" the files (i.e. make the optimizations!)
sed -i "/add[ \t][ \t]*\(e\?[a-z][a-z]\)[ \t]*,[ \t]*2$/s//rept 2 { inc \1 }/" .../*.*
    

use16
       pushfd  ; Push Flags Register onto the Stack (use 32)
       push    eax
 push    ebx
 push    edx
 call    flatmode                ; first, set up FS to access all 4G 
        
    mov eax,080000048h              ; (G)MCH Base Address Register
      mov dx,0CF8h                    ; set port address
  out dx,eax                      ; send address through the port
     mov dx,0CFCh                    ; set port data
     in eax,dx                       ; fetch data
        mov ebx,eax                     ; save the old value
        or eax,1                        ; increase data by new setting
      out dx,eax                      ; send data through port data

   and ebx,0FFFFC000h              ; mask off bits 31:14 inclusive
 add ebx,250h                    ; point to the relevant part
        mov ax,[fs:ebx]             ; fetch data at 250h address
        and ax,07FFh                    ; set Tras data bit to zero
 or ax,9000h                     ; copy data for Tras 18T
    mov [fs:ebx],ax             ; send data with 18T change

     pop     edx
 pop     ebx
 pop     eax
 popfd                           ; Pop Stack into  Eflags Register
   retf                            ; Return Far from Procedure

;----------------------------------------------------------------------
flatmode:
 ; first, calculate the linear address of GDT
        xor     edx,edx                 ; clear edx
 xor     eax,eax                 ; clear edx
 mov     dx,ds                   ; get the data segment
      shl     edx,4                   ; shift it over a bit
       cli                             ; turn off interrupts
       add     [cs:dword GDT+2],edx        ; store as GDT linear base addr
                                     ; now load the GDT into the GDTR
       lgdt    fword ptr cs:GDT         ; load GDT base (286-style 24-bit load)
     mov     bx,8                    ;1 * size DESC386 ; point to first descriptor
       mov     eax,cr0                 ; prepare to enter protected mode
   or      al,1                    ; flip the PE bit
   mov     cr0,eax                 ; we're now in protected mode
      mov     fs,bx                   ; load the FS segment register
      mov     ds,bx                   ;
   mov     es,bx                   ;
   mov     gs,bx                   ;
   mov     ss,bx                   ; load the SS segment register
      and     al,0FEh                 ; clear the PE bit again
    mov     cr0,eax                 ; back to real mode
 sti                             ; resume handling interrupts
        ret                             ;
;----------------------------------------------------------------------
GDT:
    dw  000fh                       ; limit low
 dw  GDT                         ; base lo
   db  0                           ; base mid
  db  0                           ; dpltype
   db  0                           ; lim hi
    db  0                           ; base hi

       ; this is the setup for the 4G segment
      dw  0ffffh                      ; limit low
 dw  0                           ; base lo
   db  0                           ; base mid
  db  092h                        ; dpltype
   db  0cfh                        ; lim hi
    db  0                           ; base hi
GDT_END:
    

I'm trying to switch to unreal mode in a BIOS Option ROM. I need to address 4gig memory space

MACRO Wait_INPB
        { 

@@:
     IN      AL,64H                  
    TEST    AL,00000010B            
    JNZ     @B                      

        }

MACRO Wait_OUTB   
    {

@@:
       IN      AL,64H                  
    TEST    AL,00000001B            
    JZ      @B                      

        }

;===============
; Enable A20
;===============

      Wait_INPB                       
        MOV AL,0D0H                 
        OUT         64H,AL                  
    Wait_OUTB                               
    IN      AL,60H                  
    OR      AL,00000010B            
    MOV     BL,AL                   
    Wait_INPB                       
        MOV AL,0D1H                 
        OUT         64H,AL                          
    Wait_INPB                       
    MOV     AL,BL                           
    OUT     60H,AL  

    

but the best is not to switch in unreal mode, but in protected mode.

the main problem with PM is the resident OS.
unlike RM, PM don't permitts to replace all the system.

VESA is a RM service, with optional PM services. but it's crap, i dislike the vesa mechanism. really.

unlike RM, PM don't permitts to replace all the system.